The National Survey of Family Growth is a survey of U.S. men and women of reproductive age conducted on a continuous basis by the National Center for Health Statistics (NCHS). The survey provides national estimates concerning factors related to fertility, family formation, family planning, and reproductive health including HIV infection and other sexually transmitted diseases. NCHS conducted 6 discrete cycles of the NSFG since 1973; NICHD participated in funding four of these: Cycle 3 (1982), Cycle 4 (1988, with a 1990 telephone re-interview), Cycle 5 (1995), and Cycle 6 (2002). Beginning in 2004, the survey transitioned to a continuous data collection process, with data releases occurring on a regular basis once sufficient cases have been accumulated (about every two years, subject to the availability of funds, while a contract with a survey firm is in place). This design benefits NICHD by providing larger samples at more frequent intervals than under the NSFG's old periodic design, and at the same time maximizing cost efficiency. Data collected by the NSFG provide essential information for NICHD's program planning, particularly in program areas related to contraception, fertility and infertility, pregnancy planning, pre-term birth, HIV prevention, and family change. Data from the first two years of continuous interviewing (2006-2008, n=13,495) were released in May 2010, followed by data from the full four years of interviews conducted in 2006-2010 (n=22,682). After awarding a new contract in 2010, Interviewing resumed in September 2011 and data files containing interviews from the two years from Sept 2011 through Sept 2013 (n=10,416) were released in December 2014. Interviewing continues at the rate of over 5,000 interviews per year. The next public use data file, which will contain interviews from Sept 2013 through Sept 2015 (projected n=-10,200), will be released in late 2016. Since its inception, the NSFG interviews have been conducted with respondents aged 15-44. Beginning in September 2015, the NSFG will also include men and women aged 45-49. This will enhance the substantive value of the survey and result in more efficient fieldwork.